Children aged 0 to 14 make up a growing share of hospital admissions in Bulgaria. In the 2022–2023 season they accounted for 22% of all hospitalisations; by the 2025–2026 season that figure had risen to 36.5%. Dr Kremena Parmakova, head of the infectious disease surveillance department at the health ministry, gave the figures to reporters at a seminar in Sofia.
Child hospitalisations peak in February and March. Flu and acute respiratory illness rates start climbing in late October, said Professor Neli Korsun of the National Influenza and ARI Laboratory at the National Center of Infectious and Parasitic Diseases, then drop sharply in December over the holidays.
Respiratory infections hit children aged 4 to 8 hardest, with rates higher than among adults, Parmakova said. Children in kindergartens are the main spreaders of flu. The flu vaccine cuts the risk of lab-confirmed flu in healthy children, as well as the risk of needing a doctor's visit, hospital admission or dying from flu, she said.
Bulgaria's national flu vaccination programme provides free vaccines each year for up to 17% of children under 7, plus 10,000 children with chronic illnesses. That means 55,000 children can get a free flu shot. Only a handful of EU countries, including Spain and Finland, vaccinate over 30% of children.
Since the start of July, pregnant women between 24 and 36 weeks have been able to get a free vaccine against respiratory syncytial virus (RSV). By 27 August, 260 such shots had been logged in the national health information system.
Children in Bulgaria cannot be vaccinated against RSV directly — only pregnant women can get the vaccine, Parmakova explained. Newborns get passive immunity from antibodies that cross the placenta from the mother, and vaccinating pregnant women is an established medical strategy.
Three monoclonal antibodies against RSV are in development and already in use, Professor Korsun said. One regimen requires five doses per season. The other two are given as a single dose — to babies whose mothers were not vaccinated, and to healthy infants up to 8 months old during their first RSV season.
Flu is not a mild illness, said Professor Ani Kevorkian of the Medical University of Plovdiv. It can cause neurological, cardiovascular, respiratory and musculoskeletal complications, with respiratory problems more common in children. In pregnant women, flu raises the risk of premature birth, smaller fetal size and low birth weight in newborns.
About 22,000 children under 7 end up in hospital with pneumonia every year, Kevorkian said. Up to 40% of preschool and school-age children worldwide have been given antibiotics for a flu complication. Children spread the flu virus twice as long as adults and can remain contagious for more than 10 days.
Seasonal flu is considered mild but can lead to complications, said Professor Neli Korsun. Flu viruses hit children aged 5 to 14 hardest, while people aged 30 to 64 are least affected.
The seminar was held by the Bulgarian Association for Innovative Medicine in partnership with the health ministry, and covered prevention and vaccination against seasonal flu, RSV, COVID-19, pneumococcus and chickenpox.